Fatty acid imidazoline compounds have many uses. They function as detergents, emulsifiers, corrosion inhibitors, fungicides, antistatic agents, lubricants and as bonding agents in gravel.
Fatty acid imidazoline compounds are the reaction products of carboxylic acids and polyamines. The carboxylic acids are generally fatty acids of C.sub.8 to C.sub.18 chain length and the polyamines are generally ethylene amines. In most cases, they have been obtained by condensation of ethylene diamine/ethylene diamine derivatives with long chain fatty acids.
Fatty acid imidazolines are exemplified by the general structure: ##STR1## where R is an alkyl hydrophobe radical with a preferred chain length of C.sub.12 to C.sub.18, most preferably C.sub.16 to C.sub.18. R can be saturated, unsaturated, mono unsaturated or branched alkyl groups.
The fatty acid imidazolines are readily soluble in certain non-polar solvents such as kerosene and mineral oil. These compounds, however, have two inherent shortcomings. They have generally good storage stability except when exposed to moisture. Exposure to water or humid conditions will gradually cause the imidazolines to hydrolyze and either form emulsions, precipitate, gel or separate into more than one phase.
Their other shortcoming is that they are only soluble in organic solvents while remaining relatively insoluble in water. However, their acid salts are water soluble. Neutralization with various common acids such as acetic, hydrochloric, phosphoric or sulfuric acid will make them water soluble. However, the instability in the presence of water remains inherent. Thus, aqueous solutions of fatty acid imidazolines at high concentrations do not remain stable over a long period of time and will decompose or separate into more than one phase. Further, fatty acid imidazoline salts of the water soluble acids tend to swell and form gels at high concentrations.
Oil soluble salts can be formed by neutralization with long chain fatty acids like oleic acid and tall oil, as well as, sulphonates such as L.A.S., linear alkylbenzene sulphonates. Consequently, the solubility characteristics of the fatty acid imidazolines can be altered to suit a wide variety of systems and applications.
The acid used for stabilization will also vary the stability of the resulting solution. Temperature increases will also cause a decrease in stability of the solution. Better stabilities can be achieved if some of the water is replaced with n-hexanol, n-octanol and isopropanol. Still instability problems will exist with this method, particularly at 40.degree. F.